The operation of off-highway implements such as combines and cotton harvesters under adverse environmental conditions requires protecting the operator from dust and noise. Continuing concerns for operator comfort has lead to the development of increasingly sophisticated operator enclosures which are generally referred to as cabs. A cab region of an implement is, of course, provided with the essential control mechanisms for effecting operation of the implement.
The cab region of an off-highway implement generally includes a steering mechanism for providing direction to the implement, an operator seat arranged rearwardly of the steering mechanism for allowing the operator to be comfortably seated while the implement is driven through the field, and a myriad of control mechanisms ergonomically arranged about the seat to facilitate control over both the implement and the various ancillary mechanisms associated with the implement while allowing the operator to remain comfortably seated.
A typical operator enclosure on a combine or cotton harvester substantially encloses the implement controls and includes a floor, a pair of windowed side walls or panels, at least one of which is provided with a door to provide operator access and egress to and from the cab region, a rear wall, a front wall, and a roof. The front wall of a typical combine or cotton harvester includes a vertical window arranged in front of the steering mechanism and typically spanning the distance between the floor and the roof and between the side panels.
As is known in the art, ancillary mechanisms such as a header assembly or a series of side-by-side cotton picker/stripper units are mounted directly below and extend forwardly from the front window of combines and cotton harvesters. To evaluate continuing performance and operation, the operator is desirous of visually accessing operation of the header assembly or cotton picker/stripper units as the implement is driven across the field. From the operator seat, however, the operator does not have visual access directly beneath the front window. It is common, therefore, for the operator to raise up from the seat to look beneath the front window.
While development efforts continue on providing a cab region with improved ergonomic conditions, space constraints are and continue to be a serious problem. It has been well known in the art of off-highway implements to provide a steering mechanism that includes a steering column that vertically moves or tilts from one position to another. The steering column has a steering wheel attached toward an upper end thereof. By such construction the steering wheel can be moved away from the front window and toward the operator seat such that steering movements for the implement can be effected while the operator remains comfortably seated. When the operator desires to view beneath the front window, the steering column is tilted toward the front window thereby allowing the operator to raise from the seat to visually access operations of the ancillary mechanisms directly beneath the front window
A variety of different arrangements have been developed that allow the steering column to pivot. Different positions along a steering column, e.g. the base or the midpoint, have been used as a pivot point. These arrangements, however, require complex pivoting mechanisms that do not necessarily provide for an adequate amount of tilt to achieve optimal visibility. There is also available a steering column to pivot in conjunction with the control panel of the off-highway implement. This steering column system, however, is limited by its size, and its bulk makes the arrangement cumbersome.
A variety of methods have also been developed to effectuate the tilting of the steering column relative to the off-highway implement. A tooth and gear arrangement and a clamp arrangement are but a few of these many methods available. These arrangements serve their purpose but tend to limit the potential range of motion of a tilting steering column.
The arrangements presently provided do not necessarily provide the necessary strength and rigidly to ensure that the steering column remains in a selected position when subjected to the stress often present in various situations and over an extended period of time. As an example, it is common for the operator to grasp the steering wheel and pull thereon when raising from the operator seat. Of course, if the steering column disengages or moves in response to such stress or force, the operator can become frustrated because such movements of the steering column require readjustment of the steering mechanism.
Many of the former steering mechanism arrangements are limited in their range of motion because of their construction. That is, a steering shaft typically extends lengthwise through the steering column. In order for a steering column to vertically pivot or tilt properly, the steering shaft must likewise vertically tilt or pivot. Accordingly, universal joints are provided along the length of the steering shaft. In the past, the universal joints were typically located along the length of the steering shaft corresponding to that pivot point for the steering column. Because of the position of the universal joints along the length of the steering shaft, the tiltable range of motion of the steering column is somewhat limited.
Thus, there is a need and a desire for a steering mechanism for an off-highway mechanism including a tiltable steering column that enhances visibility from the cab region of the off-highway implement as well as facilitates access and egress from the enclosure on the implement.